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KO-Lee Cutter/Grinder Revamp

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Perhaps you've seen this from other photos... It's a KO-Lee cutter grinder. It's a good platform and the table and all mechanisms are in excellent condition. I don't think this machine was used much in it's lifetime as there are very few signs of wear (hardly any at all really).

IMG_20180102_193146.jpg

The motor is the weak link. The bearings are going bad and vibration can be felt in the short shaft. The long shaft is OK. The seller told me about this when I got it. I'm guessing someone bumped a wheel really hard and damaged the bearing on that side.

Anyhow, I once had a B&S #2 surface grinder but, sold it a few years ago. It needed too much work. It took up too much space, and I rarely worked on parts more than a few inches in size. Also, the things I make do not need sub-ten-thou tolerances. I've used the KO a couple times to do some grinding on small parts within a half-thou and it works out fine. My plan when I sold the B&S was to modify the KO-Lee to handle the simple grinding tasks that come my way.

The time as come...

I'm tackling this in a couple ways and doing the work simultaneously as I go. The plan is to address a travel issue with the KO. It's got about a 12" horizontal travel which stays true the whole way. The vertical travel is about 4" and falls-off at the extremes. I'll see what I can do about that. The other idea, is to remove the old motor and replace it with a small 3 phase and design a new spindle. The spindle design will just be a larger version of the tool post spindle I dreamed-up and posted here several years ago. It's proven to be a very good design but I want to improve a couple things to handle heavier grinding wheels possessing more rotational energy.

This will be an ongoing project that I hope to finish by spring.

The drawing for the spindle is being recreated from the ground up. Here's a sneak preview. The design is still in my head and no dimensions are shown because I'm still making rough measurements of the KO-Lee platform and also, I have not settled on a convenient way to terminate the business end of the grinder shaft. Kicking about 3-4 ideas around. Here's what we have so far. You can upload the .pdf and see it in 3D.


SpindleConcept.JPG

As with the last project (https://www.hobby-machinist.com/threads/bull-nose-live-center.64859/) all the machining shots along the way will be shown and described (so you can butcher-up metal just like me).

Regards

Ray C.
 

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Comments

After the usual 15 minutes of messing with the VFD parameters just to make the motor spin, the first trial run was a success. There's good news and bad news.

The bad news: I have my doubts about this motor. Just free-running the motor, it vibrates more than I would expect also, the shaft gets hot -almost too hot to touch and finally, when it's shut off, it has no significant period of free running. Within the blink of an eye, it goes from 3600 RPM to 0 RPM and I do not have electronic braking enabled.

The good news: The spindle was running fine. The bearings inside are just greased for now. Long term this will be filled with light oil. During the 10 minute test run at 3000 RPM, nothing on the spindle got warm. Both of the sheaves are running very true.

Before making a permanent mounting assembly, I'll look into the motor issue. We'll see how things go...


IMG_20180304_170230.jpg

Ray
 
Work has slowed down on this because other matters have been keeping me occupied. This picture is not too much different than the last one however, the adjustable motor bracket is finished now. Four threaded rod studs were welded to the frame and the push/pull nuts adjust belt tension.

There's just a bunch of miscellaneous work now before the tests can begin. Right now, all the bearings are just greased but long term (and before the testing starts in-earnest) the seals and breather vent need to be installed and it will be filled with transmission fluid. All the spindle parts are done but only after it's mounted, will I be able to measure and trim the shaft and put a left-hand thread on the end.

Almost there...
IMG_20180311_182035.jpg

I sure hope this thing works. If it does, I'll make belt guards, clean it up and put some finishing touches on it. It's still pretty crude but it's getting closer to the finish line.

Ray
 
Some progress... Hopefully the video is small enough to distribute. Here's a test run while mounted on the grinder and with the spindle filled with oil. It's fairly quiet and certainly no louder than my old B&S #2.

First things first... Yes, I'm well aware there is no belt guard installed yet. These are the first runs and some level of risk is being accepted. Belt guards are indeed a part of the final plan.

When I carefully place a fingertip on either end of the shaft or on the sides of the sheaves (those are sheaves, not pulleys), it feels very smooth. For this, I am both pleased and relieved. There is one issue that will be resolved with a new belt. There's a slight vibration in the overall unit. It's not excessive but is noticeable. The sheaves are running with around 1 thou TIR and I can see the belt grooves are running dead straight and flat. The shafts are dead-on. When looking at the top of the rubber drive belt, I can see it's bouncing; I would guess about 50-75 thou. Side to side, it's running perfectly. The belt must have a thick spot in it causing it to bounce. The sheaves are perfectly aligned.
IMG_20180316_202426.jpg

It's been running at 60% for about 30 minutes now and it's barely warm to the touch. Most of the heat is from the belt. The front bearing cap is cool. We'll let it go for another 30 minutes at 100% and then I'll pull it apart and insect.

There's still a bunch of finishing work on this but, this very near the end.

Ray
 

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Well, it ran at 100% speed for an additional 45 minutes. Bearing caps, shafts etc were warm to the touch but not hot; maybe, in the 110 degree range. Oh, it was the belt causing the problem. I had another one that was 1/2" longer and it ran much smoother despite the extra distance.

I'll disassemble and inspect it tomorrow. Hopefully there will be no metal shavings in the oil. If all goes well, this weekend, I'll mount the hub on the spindle, make a wheel guard and see if it grinds metal.

Ray
 
Through all the machining the six jaws have done great ,, right. God I love mine and Ive had it thirty years . Enjoying the build isn't it great to rebuild upgrading all the time.
 
Through all the machining the six jaws have done great ,, right. God I love mine and Ive had it thirty years . Enjoying the build isn't it great to rebuild upgrading all the time.
Hi Ho, Silver... You bet, the chucks are doing great. I never used 6 jaw chucks before and I'm a believer now. They are still holding things very straight and true and they have been used quite a bit on several other projects in the shop. I have not used any of the old 3 jaw chucks since getting these and only used the 4 jaw once to hold a square piece.

Could not be happier! Thanks for asking.


Ray
 
The proof is in the pudding! It grinds really well -better than I could hope for actually...

Here's the self-centering spindle setup. Recall that the hub "floats" on two tapered cones. The drive cone is at the rear of the hub and front cone gets pushed into the front of the hub via the left hand nut. Sorry to say but, I didn't take pictures when making the locking collar. That was a piece of hardened metal made at the onset of the project. A 26 tpi left thread was put on the spindle and locking collar.

When it was snugged up and turned by hand, the hub shaft was within 0.0005 TIR. Actually, it looked to be about 0.0004".

Rear view showing the drive pins.
IMG_20180317_173736.jpg

Front view showing the front collar which centers the whole assembly when the left hand nut is tightened. I need to put a couple spanner holes on the locking collar.
IMG_20180317_173721.jpg


And of course, we had to give it a quick test run. Yes, I was wearing a full-face shield.
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So... I grabbed a nearby chunk of cast iron and this was the result after 3 passes. Step-over was about 50 thou on all passes. First was about 0.001" to make full contact. Second was 0.0005 down and third, was a phantom pass.

IMG_20180317_173418.jpgIMG_20180317_173502.jpgIMG_20180317_173942.jpg


Until I get all the safety equipment made, I won't know how flat I can make something. As far as surface finish, this is as good or better than I was able to get out of my old B&S #2.

We're pretty close to declaring success here. I just need tidy things up and get it to hold 0.0005 over a 4" x 4" piece. I'll probably need to make some level adjusting mechanism for the bracket that holds the spindle. It was built into the design but not implemented for this test phase.

Happy St. Pats Day. Time for some green beer.

Ray
 
I'm late to the party but just read the thread and enjoyed it.

I have two questions.

First, in reply #19 (Feb 3) a photo caption is "The initial scrape test showed a little low spot. " Can you describe what you mean by "initial scrape test".
Did you use Prussian blue and mate with a female taper or rub a known straight reference against it while turning or ???

Second, in reply #62 (Mar 4) you mentioned that the motor shaft got hot in a test run and that the spin-down time was very short. How were those issues addressed & resolved?

Thanks for posting.
 
I'm late to the party but just read the thread and enjoyed it.

I have two questions.

First, in reply #19 (Feb 3) a photo caption is "The initial scrape test showed a little low spot. " Can you describe what you mean by "initial scrape test".
Did you use Prussian blue and mate with a female taper or rub a known straight reference against it while turning or ???

Second, in reply #62 (Mar 4) you mentioned that the motor shaft got hot in a test run and that the spin-down time was very short. How were those issues addressed & resolved?

Thanks for posting.
Thanks 'extropic', I appreciate all the Likes you gave. FWIW, many years ago, I had more Likes than posts but back in 2012 or 2013, we got hit with destructive virus and my post count and Likes got erased.

Answer #1: To check the shaft, I coated it with bluing and used the long edge of a HSS tool blank to scrape the high spots. I checked the tool blank on a grade A table and verified it to be flat. The taper technique is also shown in this build thread: https://www.hobby-machinist.com/threads/bull-nose-live-center.64859/

Answer #2: The motor... I called the distributor and they recommended a test to let it run for a while. They were willing to accept a return if it was not satisfactory after break-in. I decided to let it run in 30 minute intervals for 4 or 5 hours. The heat problem resolved itself and is due to the fresh rubber oil seals breaking in. The vibration also smoothed out to an acceptable level but, I'm still planning to take it apart to see if I can balance the rotor a little better.

Gratuitous BS: FYI: The project is still on hold until while my shop is being reorganized. I need to build a table for that grinder and I'm not inclined to do welding until the weather improves where I can do it outside. Also, the metal frame/box needs to be sandblasted and painted -which I don't do until the garage is opened up.

Ray
 
Answer #2: The motor... I called the distributor and they recommended a test to let it run for a while. They were willing to accept a return if it was not satisfactory after break-in. I decided to let it run in 30 minute intervals for 4 or 5 hours. The heat problem resolved itself and is due to the fresh rubber oil seals breaking in. The vibration also smoothed out to an acceptable level but, I'm still planning to take it apart to see if I can balance the rotor a little better.
Ray
I had this problem when I rebuilt the spindle of my surface grinder. I bought the correct size oil seal but the shaft heated up tremendously. I don't remember the exact temp but you could not touch it for more than a split second. I didn't know you had to break them in. I ended up taking the seal off and using a V-ring (shaft mounted rotary seal).
 
G'day ray, an excellent post on a great build, I don't know where you get the time.

BTW what lathe is that? I'm guessing it's a PM 1236 from a few clues. The bits I can see of it, it looks very similar to mine LD1216, although mine has a much shorter bed, a case on necessity, I don't enough room for a longer one. But it's a nice machine I'm quite happy with it so far.
 
Thanks 'extropic', I appreciate all the Likes you gave. FWIW, many years ago, I had more Likes than posts but back in 2012 or 2013, we got hit with destructive virus and my post count and Likes got erased.

Answer #1: To check the shaft, I coated it with bluing and used the long edge of a HSS tool blank to scrape the high spots. I checked the tool blank on a grade A table and verified it to be flat. The taper technique is also shown in this build thread: https://www.hobby-machinist.com/threads/bull-nose-live-center.64859/

Answer #2: The motor... I called the distributor and they recommended a test to let it run for a while. They were willing to accept a return if it was not satisfactory after break-in. I decided to let it run in 30 minute intervals for 4 or 5 hours. The heat problem resolved itself and is due to the fresh rubber oil seals breaking in. The vibration also smoothed out to an acceptable level but, I'm still planning to take it apart to see if I can balance the rotor a little better.

Gratuitous BS: FYI: The project is still on hold until while my shop is being reorganized. I need to build a table for that grinder and I'm not inclined to do welding until the weather improves where I can do it outside. Also, the metal frame/box needs to be sandblasted and painted -which I don't do until the garage is opened up.

Ray

What's not to like? :grin:
Thanks for clarifying those points Ray.

A couple more questions please.
I'm wondering what your thinking was regarding not setting the 'standard' 3"/12" arbor taper as a design requirement? In other words, you set some other design feature(s) as higher priority than the 'standard' taper and I'm wondering which/why?
I guess intended wheel size would be a key factor. What max wheel diameter do you intend?

I'm 'watching' the thread now so I'll be patiently awaiting the completion. Great project. Thanks for posting.
 
What's not to like? :grin:
Thanks for clarifying those points Ray.

A couple more questions please.
I'm wondering what your thinking was regarding not setting the 'standard' 3"/12" arbor taper as a design requirement? In other words, you set some other design feature(s) as higher priority than the 'standard' taper and I'm wondering which/why?
I guess intended wheel size would be a key factor. What max wheel diameter do you intend?

I'm 'watching' the thread now so I'll be patiently awaiting the completion. Great project. Thanks for posting.
My pleasure... Ask all the questions you want...

The shaft is too narrow (about 7/8") for the standard taper. I want to use 1" hole diameter grinding wheels and to get any appreciable surface area on the taper, the shaft would need to taper from 7/8" down to about 1/4". I wanted the small OD of the taper to be 1/2" because I had a few 1/2" LH nuts around to use on this project. Also, with 1 HP at work, I want more than a 1/4" nut holding the wheel on.

As it turns out, I abandoned the tapered shaft idea and went with a 2-point tapered wedge setup. It works great and eliminates all the other problems at the price of a little extra machine work.

Decent grinding wheels with 1" ID and 6" OD are plentiful and cheap. As soon as you need to buy wheels with larger ID holes, the price jumps 500%.

Ray.
 
Just a quick heads-up that this project is now resurrected. I moved the last of the shop tables around and made another table for this grinder and some other grinding devices.

Today, I had some left-over paint that my wife gave me and used it on the housing parts. Not exactly a good color match to the dark grey base of the KO Lee but... oh well... It will have to do. This should be dry by tonight and I'll start re-assembly this weekend. I'll also make a wheel cover and will show pics as it progresses.

IMG_20180524_165116.jpg

Ray
 
Here's the new home for the KO Lee.
IMG_20180524_195955.jpg

Everything prior to this point was purely experimental and I was ready to toss it in the scrap pile if the results were not acceptable. It seems this "conversion" will work-out. I'm re-making some of the parts for the motor bracket. Still getting it all put back together and waiting for the paint to dry on a couple small brackets that I forgot to paint yesterday.

Right now, making the wheel safety cover. Making this up as I go and don't really know what it will look like until it's done. Time for lunch and dog walk. Probably will lay in the sun for a while and get some vitamin D.

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Ray
 
Didn't have much time today but got this put back together
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IMG_20180526_184735.jpg

Here's piece from the scrap pile that I remember hardening but forgot now what it was for. Anyhow, it's RC 37 so I put it in the lathe for a face cut then, did a quick grinding test to make sure everything was still working OK.

I'm quite pleased. The whole setup is running quite nicely. Probably hard to see in the pictures above but some rubber pads were put between the motor plate and the motor brackets. It sounds nice and smooth and feels very smooth too.

The wheel is a A80 5" so it's pretty unforgiving. Dressed the wheel and did a test. It's a keeper. When I went into this project, I was thinking it had maybe 70% odds working-out ok. Well, we made it!

IMG_20180526_185026.jpg IMG_20180526_184810.jpg


Here's the safety cover so far. I'm going to build a vacuum tube receptacle into it.
IMG_20180526_185148.jpg

This should be finished-up in a day or so.

Ray
 
Doing some fine-tuning on the hub mechanism which, so far, is working-out really well. From the onset, I knew a thin spindle shaft was going to cause problems. I truthfully though this setup of centering the hub on flexible wedge rings was going to go up in smoke and blow this whole project. In an act of desperation, I concocted that mechanism and am pleased with it now.

I've taken the whole wheel and hub off several times and using an old crappy drop-indicator on the outside of the wheel, it re-installs with TIR that appears to be less than 1 thou. I'll make a few more hubs for other wheels.
IMG_20180528_103347.jpg

IMG_20180528_103149.jpg


A couple spanner holes on the front facing locking plate are still needed. Of course, everything is left-handed threads -thus, painting the nut red so it does not get mixed-up with others.
IMG_20180528_103451.jpg

For anyone who may be new to surface grinders, buffer pads on both sides of the wheel is a highly recommended safety procedure. At high rotational speed, a wheel can oscillate. If the wheel is pressed directly against the metal hub, the vibration can (under really extreme conditions) cause the wheel to fracture. The pads absorb the vibration and also have more gripping friction than smooth metal. All around good thing to do. I cut buffer pads out of thin cardboard.

IMG_20180528_103020.jpg

Ray
 
I am confused about your hub mechanism. Do those wedge rings create force pushing out on the ID of the wheel? If so, is that safe? I always thought wheels had to be gripped in compression by the flange/washer.
Robert
 
I am confused about your hub mechanism. Do those wedge rings create force pushing out on the ID of the wheel? If so, is that safe? I always thought wheels had to be gripped in compression by the flange/washer.
Robert

The hub is solid and is no different than any other hub as far as how the wheel attaches to it. There are wedge rings on the spindle shaft that self-center the hub to the shaft. Check-out the thread at the link.

Ray
 
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